Currently there are mainly two methods for acquiring a fingerprint image. One is to acquire a fingerprint directly by means of a semiconductor chip, and the other is an optical acquisition method based on an optical lens. Each of the two methods has advantages and disadvantages. A traditional fingerprint acquisition method based on the semiconductor chip has disadvantages such as insufficient anti-static and anti-corrosion abilities. Furthermore, the large size of an optical fingerprint acquisition device make it difficult to meet requirements of a mobile device for thickness, size and the like.
The existing fingerprint image scanner, such as a thin type optical fingerprint acquisition device disclosed in Chinese Patent Application NO. 201120403301.0, generally includes an image acquisition prism, an imaging apparatus and an image processing element. The imaging apparatus further includes a lens, a photoelectric signal conversion circuit, a digital processor and the like. A relatively long light path is required to meet the requirement for light imaging, because the image acquisition prism is used as an acquisition component for light, and the lens is required to complete the light imaging of fingerprint. The image scanner must have a relatively large volume and thickness to implement the acquisition of a fingerprint image, due to a relatively large volume and thickness of the image acquisition prism and the lens, as well as factors such as the length of light path. In addition, it is difficult for the existing image scanner to meet requirements of various electronic terminals for low cost, small volume and ultra-thinness of the image scanner, due to the high cost and complex structure caused by associated components such as the image acquisition prism and the lens.